Well Log Evaluation Method of Shale Gas Flow Capacity

The gas-water two-phase seepage capacity of shale gas reservoir has an important influence on its productivity, but there is no method to evaluate the shale gas flow capacity directly by geophysical means such as logging. Three-dimensional digital core models of inorganic pores, organic pores and micro-fractures are established by core focused ion beams-scanning electron microscopy (FIB-SEM). The gas flooding water seepage of shale pores and fractures under different wetting conditions is simulated based on volume of fluid (VOF), and the characteristics of endpoint water saturation are obtained. Based on the understanding of the flow capacity of different pore types obtained from the simulation results, the equivalent flow capacity of each core can be obtained by combining the statistics of different pore types extracted from the large-scale mosaic scanning electron microscopy (Modular Automated Processing System, MAPS). Based on the analysis of petrophysical experiment and logging response, the flow capacity calculation equation and a model for evaluating flow capacity based on logging data are established. The actual logging data processing results show that the evaluation model proposed in this paper has high accuracy, and can obtain continuous shale gas flow profile. It can be used to guide shale gas exploration and development.